The general purpose of this project is to investigate the roles of autonomic nervous system activity, attention, an information processing and their interrelationships in the pathology, etiology and prognosis of psychiatric disorders. A second purpose is to determine biological and psychological processes related to ANS activity as assessed by peripheral measures such as skin conductance, heart rate and skin temperature. Subjects with diagnoses of schizophrenia, depression and neurosis are tested under conditions of rest, presentation of tones and performance on reaction time, mental arithmetic, two-flash discrimination or tachistoscopic recognition tasks. Biological mechanisms influencing ANS activity and attention are investigated by testing the effects of drugs and other treatments and by correlating these variables with enzyme activity and levels of biogenic amines and their metabolites. Psychological determinants are investigated by correlating the results with personality, mood and personal history questionnaires, by information from interviews, and by the effects of procedural variations.